This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A157706 #2 Mar 30 2012 18:59:44 %S A157706 7,75,385,1365,3850,9282,19950,39270,72105,125125,207207,329875, %T A157706 507780,759220,1106700,1577532,2204475,3026415,4089085,5445825, %U A157706 7158382,9297750,11945050,15192450,19144125,23917257 %N A157706 The z^2 coefficients of the polynomials in the GF1 denominators of A156921. %C A157706 See A157702 for background information. %F A157706 a(n) = 7*a(n-1)-21*a(n-2)+35*a(n-3)-35*a(n-4)+21*a(n-5)-7*a(n-6)+a(n-7) %F A157706 a(n) = 1/18*n^6+1/6*n^5+1/72*n^4-1/4*n^3-5/72*n^2+1/12*n %F A157706 G.f.: (7+26*z+7*z^2)/(1-z)^7 %p A157706 nmax:=27; for n from 0 to nmax do fz(n):= product( (1-(2*m-1)*z)^(n+1-m) , m=1..n); c(n):= coeff(fz(n),z,2); end do: a:=n-> c(n): seq(a(n), n=2..nmax); %Y A157706 Cf. A156921, A157702. %K A157706 easy,nonn %O A157706 2,1 %A A157706 _Johannes W. Meijer_, Mar 07 2009